What is the test for a jury to determine whether a defendant should be sentenced to death instead of life without parole?

Finally, the trial court refused defendants request that the jury be instructed: "A jury may decide, even in the absence of mitigating evidence, that the aggravating evidence is not comparatively substantial enough to warrant death." But where, as here, the jury is instructed that "[t]o return a judgment of death each of you must be persuaded that the aggravating evidence is so substantial in comparison with the mitigating circumstances that it warrants death instead of life without parole," an instruction like the one defendant proposed is unnecessary to guide the jury. ( People v. Rodrigues , supra , 8 Cal.4th at p. 1191, 36 Cal.Rptr.2d 235, 885 P.2d 1, italics omitted.)